60 research outputs found
Magnetic polarizabilities of light mesons in lattice gauge theory
We investigate the masses (ground state energies) of neutral pseudoscalar and
vector meson in lattice gauge theory in strong abelian magnetic field.
The energy of meson with zero spin projection on the axis of
the external magnetic field decreases, while the energies with non-zero spins
and increase with the field. The energy of meson decrease
as a function of the magnetic field. We calculated the magnetic
polarizabilities of pseudoscalar and vector mesons for lattice volume .
For with spin and meson the extrapolations to zero
lattice spacing have been done. We do not observe any evidence in favour of
tachyonic mode existence.Comment: 9 pages, 13 figure
The Evolution of Meson Masses in a Strong Magnetic Field
Spectra of hadrons are investigated in the framework of the
Hamiltonian obtained from the relativistic path integral in external
homogeneous magnetic field. The spectra of all 12 spin-isospin s-wave states,
generated by and mesons with different spin projections, are
studied both analytically and numerically on the lattice as functions of
(magnetic field) . Results are in agreement and demonstrate three types of
behavior, with characteristic splittings predicted by the theory.Comment: 29 pages, 7 figures, 1 tabl
Numerical study of chiral magnetic effect in quenched SU(2) lattice gauge theory
A possible experimental observation of the chiral magnetic effect in heavy
ion collisions at RHIC was recently reported by the STAR Collaboration. We
study signatures of this effect in SU(2) lattice gluodynamics with the chirally
invariant Dirac operator. We find that at zero temperature the local
fluctuations of an electric current of quarks and chirality fluctuations
increase with external Abelian magnetic field. The external magnetic field
leads to spatial separation of the quark's electric charges. The separation
increases with the strength of the magnetic field. As temperature gets higher
the dependence of these quantities on the strength of the magnetic field
becomes weaker. In the deconfinement phase the local fluctuations of the chiral
density and of the spatial components of the quarks electric current are large
and are almost independent on the external magnetic field. The local
fluctuations of the electric charge density decrease with the strength of the
magnetic field in this phase.Comment: 7 pages, 8 figures; Presented at 27th International Symposium on
Lattice Field Theory, Beijing, China, 25 Jul -31 Jul 2009; revision: minor
stylistic change
Finite-temperature chiral condensate and low-lying Dirac eigenvalues in quenched SU(2) lattice gauge theory
The spectrum of low-lying eigenvalues of overlap Dirac operator in quenched
SU(2) lattice gauge theory with tadpole-improved Symanzik action is studied at
finite temperatures in the vicinity of the confinement-deconfinement phase
transition defined by the expectation value of the Polyakov line. The value of
the chiral condensate obtained from the Banks-Casher relation is found to drop
down rapidly at T = Tc, though not going to zero. At Tc' = 1.5 Tc = 480 MeV the
chiral condensate decreases rapidly one again and becomes either very small or
zero. At T < Tc the distributions of small eigenvalues are universal and are
well described by chiral orthogonal ensemble of random matrices. In the
temperature range above Tc where both the chiral condensate and the expectation
value of the Polyakov line are nonzero the distributions of small eigenvalues
are not universal. Here the eigenvalue spectrum is better described by a
phenomenological model of dilute instanton - anti-instanton gas.Comment: 8 pages RevTeX, 5 figures, 2 table
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